1. Field of the Invention
The present invention relates to subsea hydrocarbon production. More particularly, the present invention relates to chemical injection piping as used in such subsea applications. Additionally, the present invention relates to a system for routing the chemical injection piping for the purpose of preventing hydrate formation in such chemical injection lines.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
In the art and science of recovering hydrocarbons for reservoirs beneath water, such as offshore drilling platforms and other subsea operations, it is necessary to inject chemicals into the well, wellbore, and manifolds associated therewith. Such treatment chemicals may include, but are not necessarily limited to, corrosion inhibitors, scale inhibitors, paraffin inhibitors, hydrate inhibitors, demulsifiers, and mixtures thereof. Chemical injection piping is also used in such offshore subsea applications to deliver a specific chemical to piping in subsea trees, manifolds and/or jumpers. Periodically, this chemical injection piping experiences blockages that prohibit the operator from delivering the specific chemicals. These blockages occur when produced hydrocarbons contaminate the chemical injection piping and create hydrates and/or precipitate blockages.
Whenever such blockages occur, extensive remediation efforts are required. In certain circumstances, heating elements are applied around such chemical injection piping so as to elevate the temperature of the hydrate so as to remove the blockages. The application of heat in these areas is a time consuming and difficult operation. In other circumstances, these heating techniques are ineffective in removing the blockages.
Importantly, most of the chemical injection piping extends away from the production piping associated with the manifold in such offshore subsea applications. The extension of such chemical injection piping through the cold temperature of the water associated with such offshore subsea applications will create further difficulties with hydrate formation. Often, the chemicals will need to be pumped at an elevated rate in order to avoid hydrate formation. This pressure may be in excess of the requirements necessary for effectively operating the system.
In other circumstances, the chemical injection piping will need to be removed and replaced in order to effectively remove the blockages. Under such circumstances, the production of hydrocarbons is stopped so that the repair operations can occur. This is a very costly problem for the operator of the well. As such, a need has developed so as to effectively prevent hydrate formation and blockages in chemical injection piping associated with the offshore subsea applications.
In the past, various patents have been issued relating to chemical injection piping. For example, U.S. Pat. No. 6,901,968, issued on Jun. 7, 2005 to F. H. Thomson, teaches a fluid conduit for use in the transportation of chemicals in such subsea offshore applications. The conduit comprises a flexible fluid hose encapsulated by at least one metallized layer which is formed and arranged to minimize permeation of a fluid being transported in the fluid hose. The fluid hoses have differing levels of encapsulation and, thereby permeation, along a given length according to the operational requirements of the fluid conduit/umbilical.
U.S. Pat. No. 6,663,361, issued on Dec. 16, 2003 to Kohl et al., teaches a chemical injection pump for injecting chemicals into a subsea system at depths up to 10,000 feet. The pump generates low pressures and low fluid volumes.
U.S. Pat. No. 4,979,296, issued on Dec. 25, 1990 to Langner et al., shows a flowline bundle that is twisted or braided into a permanent rope-like helical configuration. The helical flowline bundle includes a pipe twist head and a series of pipe tumblers alternating with intermediate pipe supports. The apparatus rotates and translates part of a flowline bundle while simply translating the other part.
U.S. Pat. No. 5,458,691, issued on Oct. 17, 1995 to C. K. Daniels, shows a method and apparatus for flushing fluid through the interstices of subsea umbilicals. A housing is installed in an opened end of the core with the flushing fluid introduced therein, the core elements pass through the housing. In a free-flooding umbilical installation, the flushing fluid may be gravity drained from the top of the umbilical. In other applications, the flushing fluid may be introduced under pressure.
U.S. Pat. No. 6,745,838, issued on Jun. 8, 2004 R. R. Watson, shows a chemical injection system and method for multiple wells so as to control the distribution of chemical fluid from a supply conduit into an individual petroleum well at an adjustable rate. The system includes a remotely operated two position control valve connected to the supply conduit. A cylinder having a cylinder bore with first input-output port, and a second input-output port is also provided. A fluid barrier is located within the cylinder bore such that chemical fluid flows from the supply conduit through the control valve to one end of the cylinder bore and forces the barrier to displace a fixed volume of fluid. Each operation of the directional control valve reverses travel direction of the barrier within the cylinder bore and injects another fixed quantity of fluid into the well.
It is an object of the present invention to provide a system for preventing hydrate formation in chemical injection piping.
It is another object of the present invention to provide a system that is simple to manufacture and easy to install.
It is a further object of the present invention to provide a system which effectively traps unwanted hydrocarbons by creating high and low points in the chemical injection piping.
It is still another object of the present invention to provide a system that can effectively remediate the effects of any blockages that occur in the chemical injection piping
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.